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Q & A: Launching a rocket to the sun

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Most recent answer: 09/27/2016
Q:
what kind of life insurance do i need to get to be shot into the sun when i died
- horace plomb (age 64)
Bangor, Maine, USA
A:

Launching something into the sun is hard, harder than visiting most of the planets. Transfer orbits (paths between different objects under the influence of gravity) are all about "delta-v," the velocity change required to achieve them. A larger delta-v requires a heavier, more expensive rocket with multiple stages to launch the same amount of cargo.

To fall into the sun a spacecraft would first have to escape the earth's gravity, and then after that slow down almost completely from the earth's orbital speed of about 30 km/s (~70,000 mph) around the sun. A four-stage, 3,000 ton rocket (about Saturn-V size) could only launch about 150 lbs into the sun on a direct trajectory, and it would probably cost a little more than $1 billion. If you were cremated before launch and shared space with other "passengers" maybe you could pay a fraction of that.

To get to the sun more efficiently, you could head for Jupiter instead, slightshot around it (firing the engine backwards as you go around to slow down) and fling yourself back on a collision course with the sun. With that trajectory the total delta-v would be more like 21 km/s. You might also be able to do better by using multiple passes near Venus to slow down and achieve an orbit closer to the sun. A future NASA mission called Solar Probe Plus is designed to use this method to achieve a closest approach of about 8.5 times the radius of the sun.

An even more efficient cosmic burial option would be to escape the solar system entirely, like the Voyager probes. To escape the solar system and fly off into interstellar space, a spacecraft only needs to speed up from earth's orbital velocity by about 40% (instead of reducing it by almost 100% to fall into the sun). The required delta-v would be about 17-18 km/s.

Rebecca H.


(published on 09/27/2016)

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